diff --git a/Dockerfile b/Dockerfile
index b453783..a36c4b2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -41,12 +41,13 @@ COPY assets/custom2.js /app/code/librechat/client/dist/assets/custom2.js
 COPY patch_ui_strings.py /app/code/patch_ui_strings.py
 RUN python3 /app/code/patch_ui_strings.py
 
-# Inject branding into built HTML (dist) before image is packaged
+# Inject branding into built HTML (dist) before image is packaged.
+# patch_index.py: title, custom.css/custom2.js links, and a per-build
+# x-coop-build meta (unique every build → service worker precache revision
+# changes → stale clients self-heal on deploy). Non-fatal at build.
 # rebuild marker 20261019-$(date +%s)
-RUN sed -i 's|<title>LibreChat</title>|<title>Inference Co‑op</title>|' /app/code/librechat/client/dist/index.html && \
-    sed -i '/<title>Inference Co‑op<\\/title>/a <link rel="stylesheet" href="assets/custom.css">' /app/code/librechat/client/dist/index.html && \
-    sed -i '/<link rel="stylesheet" href="assets\\/custom.css">/a <script src="assets/custom2.js"></script>' /app/code/librechat/client/dist/index.html && \
-    sed -i "s|</title>|</title>\\n    <meta name=\"x-coop-build\" content=\"$(date +%s)\">|" /app/code/librechat/client/dist/index.html && \
+COPY patch_index.py /app/code/patch_index.py
+RUN python3 /app/code/patch_index.py && \
     sed -i 's|assets/logo.svg|assets/logo.svg?v=3|g' /app/code/librechat/client/dist/assets/index.*.js && \
     rm -f /app/code/librechat/client/dist/assets/index.*.js.gz /app/code/librechat/client/dist/assets/index.*.js.br
 
diff --git a/patch_index.py b/patch_index.py
new file mode 100644
index 0000000..675da0c
--- /dev/null
+++ b/patch_index.py
@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+"""Inject co-op branding + a per-build marker into the built index.html.
+
+Non-fatal by design: if the file is missing or upstream changes shape, we
+exit 0 so a cosmetic patch can never break a version bump.
+
+The x-coop-build marker makes index.html unique per build, which changes the
+service worker's precache revision — otherwise stale clients keep running the
+old cached app shell (the "my changes never deploy" class of bug).
+"""
+import time
+
+PATH = "/app/code/librechat/client/dist/index.html"
+
+try:
+    html = open(PATH, encoding="utf-8").read()
+except OSError:
+    raise SystemExit(0)
+
+# 1. Title
+html = html.replace("<title>LibreChat</title>", "<title>Inference Co\u2011op</title>")
+
+# 2. Stylesheet + helper script (idempotent — skip if already present)
+if "assets/custom.css" not in html:
+    html = html.replace(
+        "</title>",
+        '</title>\n    <link rel="stylesheet" href="assets/custom.css">',
+        1,
+    )
+if "assets/custom2.js" not in html:
+    html = html.replace(
+        '<link rel="stylesheet" href="assets/custom.css">',
+        '<link rel="stylesheet" href="assets/custom.css">\n    <script src="assets/custom2.js"></script>',
+        1,
+    )
+
+# 3. Per-build marker → forces the service worker to refresh the precache
+if "x-coop-build" not in html:
+    marker = '<meta name="x-coop-build" content="{}">'.format(int(time.time()))
+    html = html.replace("</title>", "</title>\n    " + marker, 1)
+
+open(PATH, "w", encoding="utf-8").write(html)
+print("index.html: co-op branding + build marker injected")